In semiconductor technology, an integrated circuit pattern can be formed on a substrate using various processes including a photolithography process, ion implantation, deposition and etch. Damascene processes are utilized to form multilayer copper interconnections including vertical interconnection vias and horizontal interconnection metal lines. During a damascene process, trenches are formed in a dielectric material layer, copper or tungsten is filled in the trenches, then a chemical mechanical polishing (CMP) process is applied to remove excessive metal on the dielectric material layer and planarize the top surface.
The use of copper as a conductive interconnect material is favored in semiconductor devices because of the low resistivity and high thermal conductivity that copper provides. Copper interconnect structures are typically formed using damascene processing technology. As the critical dimensions of integrated circuits (ICs) continue to shrink, the performance of the copper-based interconnect structure faces challenges in manufacturing, device performance, and reliability.